No, not really, I mean a thin layer is acceptable and I let it form, but I am not an adept of the thick walls of cake. We have some club members that have a full ritual by poking the remaining ash in the bowl after they finish smoking it, and rattle the bowl to the point it forms a gray thin layer all around the inside of the bowl, throwing away the little that remains of the ash - it builds better cake they say. I never saw the benefit of that, nor to arguing with them, who are 110% convinced I am wrong. I for one use a pipe cleaner in a u shape, and wipe the insde of the bowl with it. Whatever gets out gets out whatever remains builds my cake, without doing it on purpose ... whenever I clean a pipe to restore, or convert to another blend, I always ream it.